1. Preheat oven to 350 degrees F.
2. Drain 1 can tomatoes and set aside.
3. Heat a large skillet over medium-high heat. Brown beef, stirring frequently. Add 1 can tomatoes and its liquid, 1/2 of the drained tomatoes, the refried beans and chili powder. Stir until well blended. Cook 5 minutes or until beginning to boil, stirring occasionally.
4. Place in shallow 2 1/2-quart baking dish. Sprinkle the remaining tomatoes evenly over all and top with corn and cheese.
5. Bake 8-10 minutes or until cheese is melted. Garnish with cilantro and sour cream, if desired. Serve warm with tortilla chips.